The invention concerns a wheel disc for a disc wheel, especially for utility vehicles, with an essentially radially extending hub fitting flange and an essentially cylindrical disc edge which can be joined to a wheel rim, and with a transition region extending between the hub fitting flange and the disc edge.
Disc wheels such as are used today primarily for utility vehicles essentially consist of two formed steel parts, namely, a wheel rim and a wheel disc, which is welded at a fitting region in the essentially cylindrical encircling disc edge at the inner circumference of the rim. The production of the wheel disc usually occurs on a flow forming machine by flow forming or flow turning, in that a steel blank is clamped in the region of the hub fitting flange between an end face of a spinning chuck and a hold-down, after which the material bordering radially outwardly on the hub fitting flange and possibly already preformed is pressed and elongated by means of flow forming under rotation of the blank against a spinning chuck in order to obtain the desired contour of the transition region and the disc edge being formed at its end. Wheel discs which are made by flow forming or flow turning have uniform surfaces on their inner and outer sides and a good texture, so that they can withstand the loads occurring in driving operation of a vehicle between rim and vehicle hub. Methods and devices for flow forming or flow turning in the production of wheel discs for vehicle wheels are known for example from DE 21 56 551, DE 196 15 675 A1, DE 198 60 732 A1 or EP 1 473 097 B1.
The problem which the invention proposes to solve is to create a wheel disc for a disc wheel of the kind mentioned above which brings a weight saving as compared to the known wheel disc forms for otherwise identical or even better strength properties.